Jean is planning to take a foreign-language class. to research how satisfied other students are with their foreign language classes, she decides to take a sample of 50 such students. the university offers classes in five languages: spanish, german, russian, french, and japanese. she will select a random sample of 10 students from each language. what best describes the sampling technique jean is using?
a) a simple random sample
b) a stratified random sample
c) a voluntary response sample

b) a stratified random sample

Step-by-step explanation:

Stratified random sampling is a sampling process that includes dividing a group into smaller  groups called strata.

The strata are established in stratified random sampling or stratification  on the basis of mutual characteristics or features of participants.

the value of v.w= -12.

step-by-step explanation:

we are given three vector r,v and w as:

r = < 5, -5, -2> ; v = < 2, -8, -8> ; w = < -2, 6, -5>

we know that r,v and w could also be represented as:

r=5i-5j-2k

v=2i-8j-8k

and w= -2i+6j-5k

where i,j and k are the unit vectors of x,y and z-axis respectively.

also we know that it has the following property:

i.i=1 ; j.j=1; k.k=1

and i.=j.i=i.k=k.i=j.k=k.j=0

i.e. when we multiply two vectors or we find it's dot product we need to only multiply the components of x coordinates with each other; y with each other and z with each other.

hence, v.w= (2i-8j- -2i+6j-5k)

                  = 2×(-2)+(-8)×(6)+(-8)×(-5)

                  = -4-48+40

                  = -12

hence, v.w= -12

step-by-step explanation:

ok so im not 100% sure but you would start by adding 5.1t and 1.9t beacuse they have the same variable. that is 7t.   then add -3.6 + 1.2 which is -2.4

so then keep that as -2.4 + 7t. i apologize if this is incorrect. best luck on your test < 3